Process of decomposing relatively high boiling point oils into relatively low boiling point oils



Feb. 9, 1937. R. A. HALLORAN ET AL 2,070,124

PROCESS OF DECOMPOSING' RELATIVELY HIGH BOILING POINT OILS INTO RELATIVELY LOW BOILING 'POINT OILS Original Filed March 21, 1927 hwl Wu ttka www W Patented Feb. 9, 1937 UNITED STATES PROCESS OF DECOIVIPOSING RELATIVELY HIGH BOILING POINT OILS INTO RELA- TIVELY LOW BOILING POINT OILS' Ralph A. Halloran and Archie L. Strout, Berkeley,

Calif., assignors, by mesne assignments, to Unlversal Oil Products Company, Chicago, 111., a corporation of Delaware I Application March 21,

1927, Serial No. 176,599

Renewed May 9, 1929 13 Claims.

This invention relates to an improvement in the art of converting relatively high boiling point hydrocarbon oils into oils of relatively lower boiling point constituents, commonly referred to as the pyrogenetic cracking of oils, and has to do more particularly with a vaporization type of cracking process wherein. the 'oil, heated to a cracking or decomposing temperature, is passed into an enlarged reaction chamber wherein vaporization takes place and from which chamber the vapors are withdrawn as distillation products while the liquid is withdrawn as heavy residuum.

As ordinarily practiced there is obtained by a vaporization type of process and from the vapors evolved and removed from the reaction or vaporization chamber the desired low boiling point or gasoline-like products and a reflux material, which latter stock is usually returned to the heating zone for retreatment, it being well known and established that by the retreatment of this reflux material the total yield of low boiling point constituents is materially increased, In instances wherein the vaporization has not been carried to the point where substantially solid or semi-solid cokey material remains, it has been common practice to withdraw the heavy residuum, usually continuously, from the vaporization chamber and to use the same as a heavy "liquid fuel oil.

In attempting to operate in accordance with the above outlined procedure and particularly on California or asphaltic base oils, it has been found that the heavy residuum produced and withdrawn from the system for use as a liquid fuel is so high in sediment content that it would not meet the specifications required for a fuel acceptable to the general market. In addition to this inherent disadvantage, it has also been found that excessively large quantities of coke were formed within the system when reasonably high yields of gasoline-like or low boiling, point constituents were obtained.

In the vaporization type of cracking process as heretofore carried out, it has been the practice to maintain thematerial within the vaporization chamber at an A. P. I. gravity much lower than the feed oil, and it has been attempted to keep the oil subjected to the treatment therein f r a long period of time. Vertical drums are often employed as reaction and vaporization chambers and resort is had in some instances to agitation of the material within the vaporization chamber in conjunction with the prolonged period of time during which the liquid remainstherein. In these vertical types of vaporization or reaction chambers, the flow of material from the inlet to the discharge end is irregular so that a part of the material is subjected to treatment for a period of time considerably in excess of the average time the material remains in the reaction chamber. In other words, as heretofore practiced there has been an absence of definite control of the flow of material through the vaporization chamber from its point of entrance to the point of withdrawal of the heavy residuum therefrom.

It is an object of this invention to provide a vaporization type of cracking process whereby a high yield of low boiling point or gasoline-like constituents may be obtained while at the same time producing a heavy liquid residuum which may be withdrawn from the system and which.

will be sufficiently low in sediment content as to meet the specifications required for a marketable fuel oil.

Another object of this invention is to provide a process of this type by which high yields of gasoJineJikeconstituents can be obtained while at the same time materially reducing the amount of coke formation which has attended the vaporization types of processes as heretofore practiced.

The vaporization process of cracking hydrocarbon oils generally requires the recycling of a very large amount of oils which are obtained as reflux'from the vapors evolved in the reaction chamber." The ratio between the amount of stock to be recycled and the amount of fresh stock to the process ranges generally from 3 to 5 parts cycled stock to 1 part of fresh oil. This necessarily imposes a large heat demand on the crack-v ing system. It is therefore another object of the present invention to provide a process of this type-by which high yields of low boiling point or gasoline-like constituents may be obtained while at the same time materially reducing the quantity of stock necessary to recycle in the system and thus reduce the heat demand on the system.

Other objects and advantages will be apparent from a description of the invention which is hereinafter set forth.

We have discovered that the sediment content of the residuum produced by the system and also the quantity of coke formed while making a given yield of low boiling point or gasoline-like constituents is a function of and directly dependent upon the gravity of the liquid oil maintained within the reaction or vaporization chamber.

tained from a California oil it is desirable to produce a heavy fuel oil residuum of about 9 A. P. I.

For example, in cracking a charging stock obgravity. A liquid residuum having such a gravity and at the same time being satisfactory as to sediment content can be produced by withdrawing from the reaction or vaporization chamber a liquid which is materially higher in A. P. I. gravity than the desired liquid residuum, and by evolving from said liquid so withdrawn from the vaporization chamber the lighter components until the residuum thus left is of the desired 9 A. P. I. gravity. By returning to.the system as a cycle stock or additional charging stock, the distillate which is thrown over during this last mentioned step and subjecting the same to retreatment throughout the system, the desired high yield of low boiling point constituents is obtained. Thus, instead of reducing the liquid oil contents within the reaction or vaporization chamber to the low A. P. I. gravity of the desired fuel oil residuum ultimately to be withdrawn from the system as has attended the prior vaporization types of cracking processes, our invention comprehends the withdrawal of the liquid oil contents from the vaporization chamber while of a lighter or higher A. P. I. gravity than the fuel oil residuum ultimately desired, distilling said liquid contents until the desired heavy residuum is produced therefrom, and returning to the system as cycle stock the constituents obtained through the distillation of the relatively high A. P. I. gravity liquid withdrawn from the reaction chamber.

We have found that the best results are obtained by maintaining a relatively small amount of oil within the reaction or vaporization chamber. By reducing the amount of oil within the vaporization chamber the time element to which the charging stock is subjected in passing once through the reaction chamber is reduced, thus tending to reduce the production of gasolinelike constituents. To compensate for this reduction and thereby maintain a desired high yield from the oil charged to the system, we employ in connection with the relatively small amount of oil maintained in the vaporization chamber a higher degree of temperature when passing the oil through the heating coils of the system. Thus by increasing the rate of cracking within the coils we compensate for the loss due to reduction in the reaction in the reaction chamber. Moreover, by reducing the amount of oil within the vaporization chamber the time element to which the heavy residuum formed is subjected is also materially reduced. This results in a reduction in the amount of coke and sediment formed. Apparently, when the heavy residuum formed is maintained for a long period of time at the high temperature of the cracking reaction, said heavy residuum degenerates into a material amount of coke and sediment. The process of the present invention has the advantage that the residuum formed by the evolution of the low boiling point constituents is withdrawn more rapidly from the zone of reaction.

In maintaining the oil content of the vaporization chamber at a relatively high A. P. I. gravity, we have found it advantageous and desirable at times to maintain a relatively high pressure upon the system and particularly upon the vaporization chamber. Pressures thus employed will generally range upwards from 250 lbs. per square inch, and when such relatively high pressure is used, distillation of those ingredients heavier than the desired low boiling point constituents will be suppressed to such an extent that for the same yield of gasoline-like bodies a smaller quantity of vapors willpass from the vaporization chamber to the fractionating element of the system, thus leaving a larger percentage of the oil' fractions in a liquid state within the vaporization chamber. This assists in raising the gravity of the total stock within the reaction or vaporization chamber, and at the same time reduces the heat requirements for re-vaporizing reflux material.

The degree of A. P. I. gravity at which this stock is maintained will depend upon the yields desired, the extent to which it is desired to reduce the sediment content of the fuel, and the extent to which it is desired to reduce the amount of coke formed by the cracking process. Furthermore, the actual gravity of the stock maintained within the evaporator for any particular pressure will depend upon the gravity of the charging stock used, the yields of gasoline-like constituents obtained and the rate of production of gasolinelike bodies for any particular size of unit. The higher the A. P. I. gravity of the oil maintained within the evaporator the greater will be the improvements in the sediment and coke conditions hereinbefore referred to.

The invention may be better understood and comprehended in its various aspects in connection with a description of a process embodying the invention and by reference to the accompanying drawing which illustrates an apparatus in which a process embodying the invention may be performed. The indicated apparatus is given for illustrative purposes only and it is to be understood that the arrangements shown and the details of construction illustrated may be widely varied without departing from the scope of our invention. Those versed in the art fully understand the methods of calculating to determine the sizes of the different parts of apparatus suitable for the particular operation they may desire to follow in the use of this process.

In the drawing, the apparatus is illustrated in diagrammatic elevation.

In the drawing, l represents a feed line through which fresh feed stock from storage or other suitable source may enter the system where it is passed by means of pump 2 through valve 3 and line 4, thence through auxiliary or secondary pumps 5 and 6. and line i into heating coils 8 which are provided in a suitable furnace 9 where the oil receives its heat and is raised to the desired temperature. As an example of a suitable temperature, we generally employ a temperature around 850 F. to 890 F. when processing a gas oil fraction of a California base oil. The temperature may be modified, depending on the character of oil processed as well as the quantity and quality of the products to be produced. It is then passed through line I 0 into a vaporization and reaction chamber l l which preferably is a relatively long and narrow cylindrical drum, mounted preferably in a horizontal position. Other types and arrangements of vessels may, however, be employed in lieu of the horizontally placed vaporization chamber. The horizontal type of reaction chamber has the advantage of insuring that all portions of oil will pass through the reaction chamber at more nearly the average time, thus tending to eliminate any part of the oil remaining therein an excessive time and degenerating into coke and sediment.

From the vaporization chamber H the vapors pass through vapor line l2 into a dephlegmating tower l3 which may be one of several different and suitable types. In this dephlegmating tower the desirable lighter or gasoline-like constituents residual heat.

pass through line 2| provided with valve 22 and thence through line 23 to suitable storage not shown in the diagram. Thus the full pressure of the system may be imposed on the products during the condensing and cooling process;

The residuum withdrawn from the evaporator Ii passes through pressure release valve 24 thence through line 25 and is discharged into vessel-=26. The release of pressure through valve 24 is as a rule sufficient to permit of the vapor- :ization from the hotliquid residuum, immediately upon its discharge into vessel 26, 'of sumcient of the volatile ingredients thereof to reduce the residuum to the gravity of the fuel oil desired. The vapors are thus evolved under their The constituents evolved will comprise a quantity of material whose boiling points are higher than those of the constituents vaporized in the vaporization chamber II. This material may be used as a' cycle stock for further' cracking. It will be obvious that the quantity-of vapors evolved in distillation vessel26 will vary, along with other factors, with the pressure carried therein and that the boiling points and gravity of the residuum may be varied and controlled accordingly. The pressure held within the distillation vessel .26 is controlled by valve 29. Pressure may be carried above or below atmospheric and steam, either in open or closed coils, as well as fired heating of the vessel 26, may be used to produce the desired results. It will further be understood that any suitable fractionating equipment may be employed in conjunction with the distillation element 26, and that refluxing by the use of a cooling medium or by the injection or intermingling of a suitable stock such as a part of the cycle stock already condensed may also be employed. In a co-pending application of Archie L. Strout, Serial No. 186,307, filed April 25, 1927, Process of decomposing relatively high boiling point oils into relatively low boiling point oils, there is described a process by which a large part of the heat in the cycle stock vapors is recovered, thus mate'- rially reducing the heat demands.

In the method as herein illustrated, these cycle stock vapors are then passed through line 21, thence through condenser coil 28 and valve 29 where they may in turn be joined with the fresh incoming feed passing through line 4. By a suitable arrangement of valves and lines, it will be evident that this cycle stock material may, if desired, be' transferred to storage such as that shown in tank 30, from which it may later be withdrawn and used, as a feed stock to the heating coils. Such heavier constituents as are separated from the gasoline-like vapors in the deph-' legmating tower 13 are passed through line 3| where they join the fresh feed stock and pass through pump 6 and line I for retreatment through the system.

In the operation of our process, we are able to maintain a liquid oil content within the vaporizing chamber H which has a relatively high A. P. I. gravity. In fact, we are able to maintain the gravity of the liquid oil within this evaporator but slightly below the gravity of the feed oil charged to the system. For example, in feed ing to the system as charging stock gas oil produced from California crude and having a gravity of 24 A. P. I. we have maintained in the vaporization chamber H a liquid residuum ranging in some instances from 16 A. P. I. gravity to 23 A. P. I. gravity depending upon the conditions of pressure and temperature employed therein while producing yields of low-boilingpermitted by the gravity of the charging stock fed to the system. the yield of low-boiling-point constituents obtained, the rate of running as well as the temperature and pressure conditions, we prefer to maintain this residuum considerably higher such as, for instance, from 21 to 24 A. P. I. gravity.

As an example illustrating the improvements effected by the process of the present invention as compared with cracking processes of the vaporization'type in operation prior to the present invention, the following data are given which data have been taken during commercial runs,

part of the data being taken from a well known prior type of vaporization process for cracking oils and part being taken from actual commercial runs of the process covered by this invention.

Conventional Process of vaporization this cracking process invention Gravity of California gas oil charged to the system 25. 0 A. P. I. 25. 0 A. P. I. Gravity of liquid withdrawn from vaporization chambeL- 9 A. P. I. 19 A. P. I. Produced low boiling point constituents (naphtha) of approx. 64 A. P. I. gravity 53% 53% Cake formed in lbs. per gallon of naphtha 35 006 Sediment in the fuel oilresiduum withdrawn from system 3.0% 15% Gravity oi the fuel oil residuum withdrawn from the system 9 A. P. I. 12. 3 A. P. I.

To one versed in the art it is apparent that by further distilling the liquid withdrawn from the vaporization chamber I I so as to give a fuel oil residuum heavier than that of l2.3 A. P. I. gravity shown above, the yield may be increased over that given above for this invention because in this way more cycle stock would be produced for re-cracking. It is also true that the process can be run to additional yields by permitting a somewhat greater formation of coke and sediment than that shown in the example above while at the same time keeping the coke and sediment within permissible limits, say .1 lb of time each portion of the oil remains in the vaporization chamb r. There is thus reduced the tendency for cracked tar which is formed within the vaporization chamber to degenerate into'coke and sediment because there is eliminated the possibility of a portion of the oil remaining in the vaporization chamber for an unduly. long period of time. Likewise, there is eliminated the likelihood of other portions of the oil being discharged from the vaporization chamber in so short a time that there is not evolved therefrom the full amount of desired low boiling point constituents contained therein. This feature is further emphasized by a technical study or mathematical consideration of the time during which various portions of the oil may remain in a vertical type of evaporator, the calculations having been made under the assumption that agitation also takes place within said vertical drum. Such an analysis shows that only 36% of the oil will remain in the evaporator for a period of time equal to the average time occupied by all the oil passing therethrough and that therefore 64% of the oil will be discharged from the evaporator before it has been there for the average length of time. This means that some of the oil remains in the evaporator for an unduly long period of time and long after all of the constituents desirable as volatile matter have been driven therefrom with the result that there is formed an undue amount of coke and high degree of sediment in the resulting fuel oil residuum, and conversely that there will be discharged from said evaporator in a relatively short period of time a material amount of oil from which very desirable volatile constituents could be evolved with little resulting formation of coke or sediment.

It will be well understood by those versed in the art that in order to realize the benefits of this invention to the fullest extent it will be desirable to use high pressures in order to prevent the vaporization of an excessive amount of fractions heavier than the desired low boiling point constituents and the consequent passing of the evolved vapors of said fractions to the fractionating column for condensation as reflux material later to be again re-vaporized as cycle stock; and that when the higher pressures are employed certain advantageous features inherent in the invention will be emphasized to a greater degree, particularly the maintaining of the liquid contents within the vaporization chamber II at a lighter or higher A. P. I. gravity, thereby reducing the tendency to form coke and sediment, and secondly, the reduction of the fuel burden upon the system through the avoidance of the re-vaporization of an excessive amount of reflux material. In practice this invention has been operated with successful results at pressures as low as 200 lbs. per'square inch and improvements in the degree of benefits accruing from the invention have been experienced as pressure were increased.

It will thus be seen that the process of the present invention provides a means by which hydrocarbon oils may be cracked to produce high yields of desired low boiling point constituents, while at the same time producing a fuel oil of desired low sediment content, and furthermore, that this is accomplished with a material reduction in the production of coke.

While in the preferred embodiment of our invention we have illustrated and described that the fresh feed is introduced directly into the heating coil, it is obvious that any desired portion of the feed may be employed for cooling purposes by introducing the same into the dephlegmating tower I 3. In such modification line 32 and valve 33 maybe employed for so conducting desired portions of the feed, valve 3 being closed should it be desired that all of the feed be introduced into said dephlegmating tower by way of line 32. The line 32 connects with a coil pipe 34 in the upper part of the dephlegmator i3 so that in the upper part of the dephlegmator the cooling ,of the vapors is effected by indirect transfer of heat to the coil. The coil pipe 34 discharges the oil then into the dephlegmator l3 so that in the remainder of the dephlegmator the oil operates as a scrubbing agent in the refluxing action of the vapors in dephlegmator l3. It

will also be understood that such quantities of feed so used for cooling purposes may be introduced into the tower by spraying thereinto or by conducting it through closed coils for heat exchange purposes either therein or in other suitable manner.

It is understood that the process of the present invention may be performed in an apparatus which includes a battery of like sets of apparatus, and that the cycle stock material from one unit of such a battery may, if desired, be recycled to the reaction and vaporization chamber of another unit of the series. Moreover, the distillation chamber 26 may serve a plurality of vaporization and reaction chambers.

The process is capable of numerous other modifications and is not therefore limited to the particular embodiment described for illustrating the invention, but is of the scope set forth in the accompanying claims.

We claim:

1. A continuius process of decomposing oils into a relatively high yield of relatively low boiling point oils and a substantially sediment free liquid residuent suitable for fuel oil which includes passing the oils in a relatively small stream once through a heating zone wherein the oils are rapidly heated to a temperature of not less than 800 F., while subjected to a pressure of not less than 200 pounds per square inch, discharging said oils from said heating zone into a. vaporizing zone without substantial reduction of pressure and through which a substantially uniform rate of flow and separate discharge of desired low-boiling point vapors and unvaporized oils is maintained and in which further decomposition takes place but substantial degeneration of the heavy residuents of cracking into a material amount of coke is prevented by maintaining in said vaporizing chamber such a relation of pressure to temperature therein as to provide dilution of said heavy residuents with a proportion of lighter oils not readily decomposed into coke under such temperature and pressure and by removing such diluted heavy residuents therefrom before such residuents have\been subjected to decomposing conditions for such time as might othinch tothe maximum temperature of the process and to a temperature sufficient to effect a rapid cracking reaction, passing the oils directly therefrom into a vaporizing zone without substantial reduction of pressure and wherein further decomposition takes place, maintaining a uniform rate of flow of the vaporized and unvaporized oils from said heating zone into and through the vaporizing zone and a separation and separate discharge of desired low boiling point vapors and unvaporized oil from said vaporizing zone, wherein is maintained a pressure suflicient under the temperature conditions of the operation to maintain the heavy residuents of cracking diluted with a material quantity of oils suitable for further cracking, and eflecting the discharge of said diluted residuents from said vaporizing zone before degeneration into a material amount of coke and sediment can take place and whereby there may be obtained from said diluted liquid residuents such substantially sediment free fuel oil.

3. A continuous process of decomposing oils I into relatively low boiling point oils and a liquid residuent substantially free from sediment and which is suitable for fuel oil which includes rapidly passing the oils in a relatively small stream once through a heating zone wherein the oils are rapidly heated to a relatively high cracking temperature under a pressure of not less than 200 pounds per square inch to produce a relatively high yield of low boiling point oils, continuously and at a uniform rate passing the oils into and through a vaporizing zone wherein further decomposition occurs and wherein there is a drop of temperature by vaporization and the pressure is substantially maintained whereby the residuent formed by the cracking operation is diluted with a material and suflicient quantity of oil suitable for further cracking and from which vaporizing zone the desired low boiling point vapors and liquid oils are separately discharged so that thereby and by continuously removing the vapors and liquid oil, at such a relation of speed to volume of oil in said zone the residuent formed by the cracking reaction within said zone is retained therein only for a length of time insuiiicient to permit said residuent undergoing substantial degeneration into coke, reducing said removed liquid by distillation under reduced pressure to a substantially sediment free liquid residuent suitable for use as fuel oil while recovering a clean distillate of oil suitable for further cracking and returning it to the cracking operation.

4. A continuous process of decomposing oils into a relatively high yield of relatively low boiling point oils and a substantially sediment free liquid residuent suitable for fuel oil which includes passing the oil in a relatively small stream once through a heating zone wherein the oils are rapidly heated to a temperature of not less than 800 F., while subjected to a pressure of not less than 200 pounds per square inch, discharging said oils from said heating zone into a vaporizing zone without substantial reduction of pressure and through which a substantially uniform rate of flow and separate discharge of desired low boiling point vapors and unvaporized oils is maintained and, in which further decomposition takes place but substantial degeneration of the heavy residuents of cracking into a material amount of coke is prevented by maintaining in said vaporizing chamber such a relation of pressure to temperature therein as to provide dilution of said heavy residuents with a proportion of lighter oils not readily decomposed into coke under such temperature and pressure and by removing such diluted heavy residuents therefrom before such residuents have been subjected to decomposing conditions for such time as might otherwise cause degeneration, releasing pressure from said diluted heavy residuents withdrawn from said vaporizing zone to vaporize therefrom oils suitable for further cracking, and collecting the vapor of such distillation whereby there is secured from the unvaporized portion of said diluted liquid residuents a substantially sediment free fuel oil.

5. A continuous process of decomposing oils into a relatively high yield of relatively low boiling point oils and a substantially sediment free liquid residuent suitable for fuel'oil which includes passing the oils in a relatively small stream once through a heating zone wherein the oils are rapidly heated to a temperature of not less than 800 F., while subjected to a pressure of not less than 200 pounds per square inch, discharging said oils from said heating zone into a vaporizing zone through which a substantially uniform rate of flow and separate discharge of desired low boiling point vapors and unvaporized oils is maintained and in which further decomposition takes place while substantial degeneration of the heavy residuents of cracking into a material amount of coke is prevented by maintaining in said vaporizing chamber a pressure of not less than 200 pounds per square inch whereby the heavy residuents of cracking are maintained diluted with lighter oils and at a cracking temperature and by maintaining such a relation of pressure to temperature therein as to thereby provide the dilution of said heavy residuents with a proportion of lighter oils not readily decomposed into coke under such cracking temperature and pressure, and by removing such diluted heavy residuents therefrom before such residuents have been subjected'to decomposing conditions for such time as might otherwise cause such degeneration, whereby there may be obtained from said diluted liquid residuents a substantially sediment free fuel oil.

6. A continuous process of decomposing oils into relatively low boiling point oils and a liquid residuent substantially free from sediment and which is suitable for fuel oil which includes rapidly passing the oils in a relatively small stream once through a heating zone wherein the oils are rapidly heated to a relatively high cracking temperature under a pressure of not less than 200 pounds per square inch to produce a relatively high yield of low boiling point oils, continuously and at a uniform rate passing the oils into and through a vaporizing zone, wherein further decomposition occurs and from which the desired low boiling point vapors and liquid oils are separately discharged, and wherein a pressure of not less than 200 pounds per square inch is maintained whereby the residuents formed by the cracking operation are maintained diluted with a material and suflicient quantity of oil suitable for further cracking, without reduction of the temperature except such drop of temperature as is incident to vaporization, a cracking temperature of said diluted residuents being maintained, so that by said dilution of the residuents of crack ing and by continuously removing the vapors and liquid oil at such a relation of rate to volume .of oil in said zone, the residuent formed by the cracking reaction within said zone is retained into relatively low boiling point oils and a liquid residuent substantially free from sediment and which is suitable for fuel oil which includes rapidly passing the oils in a relatively small stream once through a heating zone wherein the oils are rapidly heated to a relatively high cracking temperature under a pressure of not less than 200 pounds per square inch to produce a relatively high yield of low boiling point oils, continuously and at a uniform rate. passing the oils into and through a vaporizing zone, wherein further decomposition occurs and from which the desired low boiling point vapors and liquid oils areseparately discharged, and wherein a pressure of not less than 200 pounds per square inch is maintained whereby the residuents formed by the cracking operation are maintained diluted with a material and sufficient quantity of oil suitable for further cracking, without reduction of the temperature except such drop of temperature as is incident to vaporization, a cracking temperature of said diluted residuents being maintained so that by said dilution of the residuents of cracking and by continuously removing the vapors and liquid oil at such a relation of rate to volume of oil in said zone the residuent formed by the cracking reaction within said zone is retained therein only for a length of time insufficient to permit said residuent undergoing substantial degeneration into coke reducing said removed liquid by distillation under reduced pressure to a substantially sediment free liquid residuent suitable for use as fuel oil while recovering a clean distillate of oil suitable for further cracking and returning it to the cracking operation.

8. A continuous process of decomposing oils into a relatively high yield of relatively low boiling point oils and a substantially sediment free liquid residuent suitable for fuel oil which includes passing the oils in a relatively small stream once through a heating zone wherein the oils are rapidly heated under superatmospheric pressure of not less than 200 pounds per square inch to the maximum temperature of the process and to a temperature sufiicient to effect a rapid cracking reaction, passing the oils directly therefrom into a vaporizing zone wherein further decomposition takes place, maintaining a uniform rate of flow of the vaporized and unvaporized oils from said heating zone into and through the vaporizing zone and a separation and separate discharge of desired low boiling point vapors and unvaporized oil from said vaporizing zone, wherein is maintained a pressure of not less than 200 pounds per square inch thereby maintaining at cracking temperature the heavy residuents of cracking diluted with a material quantity of oils not readily decomposed into coke under such pressure and temperature, and effecting the discharge of said diluted residuents at cracking temperature from said vaporizing zone before degeneration into a material amount of coke and sediment can take place and whereby there may be obtained from said diluted liquid residuents such substantially sediment free fuel oil.

9. In a continuous process of decomposing oils into relatively low boiling point oils and a liquid residuent substantially free from sediment and which is suitable for fuel oil rapidly passing the oils in a relatively small stream once through a heating zone wherein the oils are rapidly heated to a relatively high cracking temperature under a pressure of not less than 200 pounds per square inch to produce a relatively high cracking rate, continuously and at a uniform rate passing the oils into and through a vaporizing zone in which further decomposition takes place from which the desired low boiling point vapors and liquid oils are separately discharged and where- 'in there -is a drop of temperature incident to the cracking and vaporization, without lowering the temperature of the unvaporized oils below cracking or decomposition temperature, maintaining a super-atmospheric pressure throughout said vaporizing zone insufficient to prevent vaporization of the desired low boiling point oils but suflicient to prevent vaporization of a portion of relatively high boiling point oils suitable for further cracking whereby the residuents formed by the cracking reaction are diluted with a material and sufiicient quantity of oil suitable for further cracking, so that thereby and by the continuous removal of the vapors and liquid oil at such a relation of withdrawal to volume of the oil in said zone the residuents formed by the cracking reaction within said zone are retained therein only for a length of time insufficient to permit said residuents undergoing substantial degeneration into coke, reducing said removed liquid by distillation under reduced pressure to a substantially sediment-free liquid residuent suitable for use as fuel oil while recovering a clean distillate of oil suitable for further cracking and returning it with fresh feed to the cracking operation.

10. In a continuous process of decomposing oils into relatively low boiling point oils and a liquid residuent substantially free from sediment and which is suitable for fuel oil, rapidly passing the oils in a relatively small stream once through a heating zone wherein the oils are rapidly heated to a relatively high cracking temperature under a pressure of not less than 200 pounds per square inch to produce a relatively high cracking rate, continuously and at a uniform rate passing the oils into and through a vaporizing zone in which further decomposition takes place from which the desired low boiling point vapors and liquid oils are separately discharged and wherein there is a drop of temperature incident to the cracking and vaporization, without lowering the temperature of the unvaporized oils below cracking or decomposition temperature, maintaining a superatmospheric pressure throughout said vaporizing zone insufficient to prevent vaporization of the desired low boiling point oils but suflicient to prevent vaporization of a portion of relatively high boiling point oils suitable for further cracking whereby the residuents formed by the cracking reaction are diluted with a material and sufficient quantity of oil suitable for further cracking, so that thereby and by the continuous removal of the vapors and liquid oil at such a relation of withdrawal to volume of the oil in said zone the residuents formed by the cracking reaction within said zone are retained therein only for a length of time insuificient to permit said residuents undergoing substantial degeneration into coke, reducing said removed liquid by disti11ation to a substantially sediment-free liquid residuent suitable for use as fuel oil while recovering a clean distillate of oil suitable for further cracking and returning it with fresh feed to the cracking operation.

11. A continuous process of converting high boiling point oils into relatively low boiling point oils and a substantially sediment-free liquid residuent suitable for fuel oil which includes passing the oils in a restricted stream once through a heating zone wherein the oils are rapidly heated under superatmospheric pressure to the maximum temperature of the process which is sufflcient to effect a rapid cracking reaction, passing the oils directly therefrom into a vaporizing zone without substantial reduction of pressure and wherein further cracking takes place maintaining a uniform rate of flow of the vaporized and unvaporized oils from said heating zone into and through the vaporizing zone and a separation and separate discharge of desired low boiling point vapors and unvaporized oil from said vaporizing zone, wherein is maintained a pressure suificient under the temperature conditions of the operation to thereby restrict the extent of vapor separation, and to maintain the heavy residuents of cracking diluted with a material quantity of relatively lighter oils suitable for further cracking, effecting the discharge of said unvaporized liquid oil from said vaporizing zone at such a rate as to thereby pass the diluted residuents from said vaporizing zone before degeneration to a material amount of coke and sediment can take place and whereby there may be obtained from said diluted liquid residuents a substanti'ally sediment-free fuel oil.

12. A process of cracking hydrocarbon oil which comprises heating the oil to cracking temperature as it flows under superatmospheric pressure through a heated coil, passing said oil into an enlarged vaporizing zone maintained under superatmospheric pressure wherein separation of Vapors and liquid occurs, removing the separated vapors, maintaining upon the oil and vapor in said vaporizing zone a pressure sufi'icient under the temperature conditions of the operation to restrict the extent of vapor separation and to maintain the heavy residuents of cracking diluted with a material quantity of relatively lighter oils suitable for further cracking, withdrawing the liquid oil from said enlarged chamber at such a rate as to thereby pass the diluted residuents from said reaction chamber before degeneration to a material amount of coke and sediment can take place, and whereby there may be obtained from said diluted liquid residuents a substantially sediment-free fuel oil.

13. A process of cracking hydrocarbon oil which comprises heating the oil to cracking temperature as it flows under superatmospheric pressure through a heated coil, passing the oil thence into an enlarged reaction chamber maintained under superatmospheric pressure wherein separation of vapors and liquid occurs, removing the separated vapors, maintaining upon the oil and vapor in said reaction zone a pressure sufficient under the temperature conditions of the operation to restrict the extent of vapor separation and to maintain the heavy residuents of cracking diluted with a material quantity of relatively lighter oils suitable for further cracking, withdrawing the liquid oil from said enlarged chamber at such a rate as to thereby pass the diluted residuents from said reaction chamber before degeneration to a material amount of coke and sediment can take place and whereby there maybe obtained from said diluted liquid residuents a substantially sediment-free fuel oil,

. expanding the withdrawn liquid oil by partial release of pressure into a flash chamber and effecting distillation by means of the contained heat of said liquid under suchreduced pressure.

RALPH A. HALLORAN. ARCHIE. L. STROUT. 

